The invention relates to methods and apparatus for topical intra-uterine anesthesia.
Physicians commonly use topical anesthesia to reduce pain associated with uterine manipulations during gynecological procedures. Conventional anesthesia devices and methods suffer from several disadvantages. An example of a conventional, commercially available device for topical intra-uterine anesthesia is depicted in FIG. 1. Such devices 10 typically include a frontal, soft perforated tube 12 attached to a pliable acorn 14, which is connected to a syringe 16. The method for using such devices involves inserting the tube 12 into the cervical canal (normally collapsed) until the pliable acorn 14 abuts the external cervical os. The syringe 16 is used to introduce an anesthetic (e.g., Lidocaine(copyright) or Marcaine(copyright)) through the perforated tube 12 to anesthetize the immediately surrounding tissue. The pliable acorn 14 blocks the cavity of the cervix and prevents the back-flow of the anesthetic through the vagina. After the pliable acorn 14 is withdrawn, a small portion of the anesthetic may leak out; the remaining anesthetic is predominantly absorbed by the cervical mucous membrane.
Such conventional anesthesia devices suffer from several disadvantages. For example, these devices do not include a frontal portion that is long enough to reach the tubal ostium. Consequently, conventional anesthesia devices permit application of anesthetic to the cervix, which is of limited clinical use, rather than the target area, which is mainly the tubal ostium. The straight angle of the conventional frontal tube makes it difficult to direct the anesthetic towards the tubal ostium. Conventional anesthesia devices also inject the anesthetic into the cavity through the cervix, which displaces intrauterine debris such as mucus and menstrual blood toward the fundus and uterine cornua. This prevents the anesthetic from reaching its target, i.e., the mucosal surface of the uterine cavity and cornua.
Furthermore, such conventional anesthesia devices are typically designed with rigid frontal tubes made out of rigid plastic or metal material. Such construction, however, makes it difficult to direct the anesthetic to desired regions of the patient""s uterus. Further, any effort to direct the frontal tube in a particular direction is likely to result in increased discomfort to the patient.
Another conventional mechanism for anesthetic application to the cervix involves the use of a procto-swab or a cotton tipped applicator coated with anesthetic gel (e.g., benzocaine 20% gel, 2% lignocaine gel, or Instillagel(copyright)[2% lignocaine+0.25% chlorhexidine]). The swabs are inserted through the vagina into the cervix. This process also has several disadvantages. For example, the gel is hydrophobic and is rendered ineffective to some extent as it passes through the mucus present in the vagina and the cervix. Another disadvantage is that the gel typically rubs off on the vaginal wall, reducing the amount of gel applied to the cervix and also resulting in application of anesthetic to an undesired region of the patient""s genital tract. The swab is also typically made of rigid material to increase the ease of the insertion. However, the rigidity of the swab makes it difficult to direct the gel to the desired region. Another significant disadvantage of using a swab is that it increases the likelihood of passage of pathogens from the lower to the upper genital tract.
The invention relates to a topical intra-uterine anesthesia device (IUAD) which is intended to apply anesthetic to the mucosal surface of the uterine cavity and the tubal ostium. In the preferred embodiment of the invention, an intrauterine applicator is combined with an injection device, such as a syringe. For purposes of this description, this invention is described in the context of using a syringe. The applicator preferably includes a thin, hollow, slightly inclined, frontal tube having an orifice at the distal tip of the tube and one or more orifices on the sides of the tube near the distal tip. In use, the applicator is inserted through the vagina into the cervical cavity, and is gently pushed until the tip reaches the fundus. The slight inclination of the frontal tube allows the anesthetic to be directed towards either one or the other tubal ostium and the cornua of the uterus. If the IUAD is used without an acorn for preventing the back-flow of the anesthetic through the vagina, observation of anesthetic back-flow through the vagina may provide evidence of the sufficiency of volume used of the anesthetic.
The orifices at the distal tip of the hollow tube perforate the wall of the tube at a forward oblique angle. This provides a preferential path for the anesthetic. This preferential path is important because the anesthetic will be directed toward the fundus or ostium thereby displacing intra-uterine debris toward the lateral walls of the uterine cavity. Once the anesthetic material fills the space near the fundus and tubal ostium, it will continue to displace intra-uterine debris toward the cervix and out into the vagina. Displacement of the intrauterine debris away from the mucosal surface allows the anesthetic material to establish direct contact with the mucosal surface. Direct contact between the anesthetic and mucosal surface is necessary for the anesthetic to take effect.
The frontal tube is preferably made of a semi-flexible plastic or other material appropriate for the particular application. As described below, the frontal tube may have more than the orifice at the distal tip of the tube. In particular, the frontal tube may include orifices on the sidewalls. The orifices at the distal tip of the hollow tube are positioned, shaped, and aligned such that the anesthetic is directed toward the tubal ostium and the fundus, regardless of whether one or more of the orifices is obstructed by (1) the fundus or other uterine wall; or (2) anatomic variations of an individual""s uterus.
Embodiments of the invention provide significant advantages in that the physician can apply anesthetic to the mucosal surface of the tubal ostium even without accurately locating the same. Consequently, the efficiency of applying topical anesthetic to the mucosal surface of the uterine cavity and uterine cornua is significantly increased.